Avian movements in a modern world - cognitive challenges

Different movement patterns have evolved as a response to predictable and unpredictable variation in the environment with migration being an adaptation to predictable environments, nomadism to unpredictable environments and partial migration to a mixture of predictable and unpredictable conditions. Along different movement patterns different cognitive abilities have evolved which are reviewed and discussed in relation to an organism’s ability to respond to largely unpredictable environmental change due to climate and human-induced change and linked to population trends. In brief, migrants have a combination of reliance on memory, low propensity to explore and high avoidance of environmental change that in combination with overall small brain sizes results in low flexibility to respond to unpredictable environmental change. In line with this, many migrants have negative population trends. In contrast, while nomads may use their memory to find suitable habitats they can counteract negative effects of finding such habitats disturbed by large-scale exploratory movements and paying attention to environmental cues. They are also little avoidant of environmental change. Population trends are largely stable or increasing indicating their ability to cope with climate and human-induced change. Cognitive abilities in partial migrants are little investigated but indicate attention to environmental cues coupled with high exploratory tendencies that allow them a flexible response to unpredictable environmental change. Indeed, their population trends are mainly stable or increasing. In conclusion, cognitive abilities have evolved in conjunction with different movement patterns and affect an organism’s ability to adapt to rapidly human-induced changes in the environment

Retreat, detour or advance? Understanding the movements of birds confronting the Gulf of Mexico

During migration, birds must locate stopover habitats that provide sufficient resources to rest and refuel while en route to the breeding or non-breeding area. Long-distance migrants invariably encounter inhospitable geographic features, the edges of which are often characterized by habitat limited in food and safety. In response, they often depart in directions inconsistent with reaching their destination, presumably searching for better habitat. We used automated radio telemetry to track 442 individuals of five species to investigate the behavior of migratory birds as they departed edge habitat along the northern Gulf of Mexico coast during autumn from 2008 to 2014. Most migrants (75%) retreated inland or detoured around rather than advanced across the Gulf, but this depended on bird species and fat-based energy stores. Most individuals in lean condition or of smaller bodied species tended to retreat or detour, rather than advance, when departing from the coast. Twenty-one percent of all birds that departed the coast in 2013–2014 were redetected over 45 km inland, providing a unique opportunity to compare stopover duration, departure times and travel speeds between migrants that retreat away from the coast and those that continue to advance toward their destination. Individuals that retreated the coast and were redetected inland spent ~1 day on the coast before retreating inland, where they spent 11 days before resuming migration. Further when those same individuals retreated from the coast, they departed around evening civil twilight, whereas those that advanced from inland habitats departed after evening civil twilight. Travel speeds were slower for individuals retreating inland compared to those advancing towards the coast from inland habitats. The differences between retreating and advancing individuals suggest how an individual\u27s drive to feed or fly influences behavior. Our study illustrates how the sum of individual decisions can shape habitat use, landscape-scale movements and migration strategies